I think it has to be an availablity and marketing issue.

You know the simultaneous book release of Harry Potter, even though you can get soft copies online soon after release. The fact that simultaneous, multi language release of the Harry Potter series has indeed a great effect on sales.

At last the comic/manga, format does not seem to have caught up in terms of commercial release.

Once again, a touchy issue. But it does not mean that I do not enjoy the near instantaneous release of manga in fan-translated release, or that I do support the sales of manga by licensed publisher.